If you can’t connect to an AirPort network, and the network requires a password that you’ve tried to enter correctly, try the following:

1. Open the Console utility in your Utilities folder.
2. Choose File > Open System Log.
3. Look for a line that includes the message:
kernel[0]: AirPort: Rx’d mesg P-1
4. If the message is there*, try the steps that follow.
5. Open System Preferences, and click Network.
6. Edit AirPort. (If you see the Network Status list, double-click AirPort.)
7. You might have AirPort set to “By default, join: A Specific Network.” Confirm that the network name is correct.
8. Here’s the important part. Re-enter the network password.
9. Click Apply Now. (Don’t change your Location before clicking Apply Now, or your changes probably won’t be saved.)

*If you aren’t getting that error, I don’t know what the problem is. This tip won’t help you if you’re trying to get into a network where you don’t know the password.